1. Field of the Invention
The present invention relates to systems and methods for recording and playing back media programs embodied in media streams, and in particular to a system and method for secure storage and retrieval of video frames temporarily stored in queues and buffers.
2. Description of the Related Art
Compression technologies have made the storage and transmission of media programs having audiovisual information to consumers feasible. Such video compression techniques, hereinafter generically referred to as compressed packetized transport (CPT) techniques, typically break the media program into a plurality of frames that are compressed using spatial and/or temporal encoding techniques. One example of a CPT is the H.264 standard, which is an MPEG-4 Part 10, Advanced Video Coding (MPEG-4 AVC) standard that is described in more detail at www.en.wikipedia.org/wiki/H.264/MPEG-4_AVC.
Compressed media programs can be transmitted via satellite, cable, terrestrial wireless transmission, or the Internet, or received in analog form and compressed locally. Once received by a suitable device, the media programs may be decoded and/or decrypted (if encoded and/or encrypted) and provided to a display device for presentation to the user.
The transmission of such media programs is often accomplished by use of HLS (HTTP Live Streaming), which is an HTTP (hypertext transfer protocol) based media streaming protocol that works by breaking up an incoming media stream into a sequence of small HTTP-based file downloads known as chunks, with each chunk being a small portion of a potentially unbounded transport stream. More information on HLS can be found at www.en.wikipedia.org/wiki/HTTP_Live_Streaming.
To ensure that media program recordings are not subjected to unauthorized use, they are typically encrypted before transmission and storage, for example, using an AES-128 CBC (Advanced Encryption Standard, 128 bit key length, Cipher Block Chaining) encryption with PKCS7 (Public Key Cryptography Standard #7) padding, which are described at www.en.wikipedia.org/wiki/Advanced_Encryption_Standard and www.en.wikipedia.org/wiki/PKCS, respectively. However, there may still remain instances during processing where the media program is temporarily stored in an unencrypted form in queues or buffers.
In view of the foregoing, there is a need for systems and methods for securely storing the contents of queues and buffers in a form that prevents unauthorized access but does not impede the processing of the media programs. This disclosure describes systems and methods that satisfy that need.